1. The Field of the Invention
This invention relates to heat recoverable material having integral latching means associated therewith so that the material may be wrapped around a structure, such as a cable, the ends latched together and heated so that it recovers towards its original smaller size.
2. The Prior Art
The present invention is a novel improvement and a departure from at least the following:
______________________________________ U.S. Pat. No. Patentee Class/Subclass ______________________________________ 3,455,336 Ellis 138/156 4,123,047 Koht et a1 269/238 ______________________________________
A desirable method of repairing a tear in the insulation of a cable or a hole in a pipeline is to shrink a sleeve of heat recoverable material down around the damaged site. However, it may be impossible or impractical to place a sleeve onto the cable or pipe for one reason or the other. Accordingly, workers in the field have been working on lengths of material, referred to as a "wrap", which can be wrapped around the structure and then shrunk down. However, because the recovery forces in the material are so great, difficulties have been encountered in keeping the ends of the wrap together. Adhesives have been tried without great success. The first successful mechanical means for holding the ends together was disclosed by Ellis. In molding his material, rails on each end were molded as an integral part. Each rail has an enlarged, non-symmetrical top portion and a reduced neck portion to provide a downwardly facing shoulder. These rails are physically confined during expansion of the wrap. In use, the wrap is wrapped around a structure and, with the two rails held together, a metal, C-shaped fastener is placed across both rails by sliding with the sides of the fastener being positioned under the shoulders. Upon the application of heat, the wrap material recovers down into a tight band around the structure. The rails, not being originally expanded, retain their size and shape during the recovery and thus, the integrity of the latch is maintained. Where a suitable heat activated adhesive is used, or where the material is self bonding, the metal fastener and rails may be cut away to reduce the profile of the wrap.
Koht and others subsequently disclosed another mechanical device for gripping and keeping the two ends of the wrap closed during recovery. Their mechanical device consists of a plurality of manually operable clips connected together in a given length by means of a fiexible cable. The clips have a pair of cooperating jaws which engage and clamp the two laid-together ends of the wrap. The heat recoverable material of Koht et al differs from that of Ellis in that the entire length of material is expanded including the ends.